This Nutshell Handbook® is far and away the most comprehensive book ever written on sendmail, the program that acts like a traffic cop in routing and delivering mail on UNIX-based networks. Although sendmail is used on almost every UNIX system, it's one of the last great uncharted territories--and most difficult utilities to learn-- in UNIX system administration.This book provides a complete sendmail tutorial, plus extensive reference material on every aspect of the program. What's more, it's authoritative, having been co-authored by Eric Allman, the developer of sendmail, and Neil Rickert, one of the leading sendmail gurus on the Net.This book covers both IDA sendmail and the latest version (V8) from the University of California, Berkeley. It also covers the standard versions available on most systems, such as those found on Sun and DEC/Ultrix workstations.The book is divided into four parts. Part One is a tutorial on understanding sendmail from the ground up; starting from an empty file, it has the reader work through exercises, building a configuration file and testing the results. Part Two covers practical issues in sendmail administration. Part Three is a comprehensive reference section, while Part Four consists of appendices and a bibliography.

Our look is the result of reader comments, our own experimentation, and feedback from distribution channels. Distinctive covers complement our distinctive approach to technical topics, breathing personality and life into potentially dry subjects. The animal featured on the cover of sendmail is the flying fox, a species of fruit bat found chiefly on the islands of the Malay-Indonesia archipelago. Of about four thousand species of mammals, nearly one-quarter are bats; and of these, 160 are fruit bats. Sixty of the larger fruit bats make up the flying foxes, the largest having a wingspan of five feet. As opposed to the smaller insect-eating bats, who navigate by echolocation, fruit bats depend on a keen sense of sight and smell to perceive their environment.They roost in trees by day, sometimes in extremely large numbers called "camps." They hang from branches by one or both feet, wrap themselves in their wings, and sleep the day away. On very hot days, these bats keep cool by fanning themselves with their wings.Greatly elongated fingers form the main support for the web of skin that has allowed these mammals, alone, to master true flight. At sunset they awaken from their slumber and begin their nocturnal ramblings. A flying fox must flap its wings until it becomes horizontal to the ground before it can let go and fly away. Once airborne, they use their sensitive sense of smell to detect where flowers are blooming or fruits have ripened. Unlike most animals, fruit bats cannot generate vitamin C (a limitation shared by humans and guinea pigs); thus, it is supplied by fruit in the diet. Flying foxes can range up to forty miles for food. Once a target is located, they are faced with a difficult landing. Sometimes they will simply crash into foliage and grab at what they can; other times they may attempt to catch a branch with their hindfeet as they fly over it and then swing upside-down; some will even attempt a difficult half-roll under a branch in order to grip it in the preferred position. Once attached and hanging, they will draw the flower or fruit to their mouths with a single hindfoot, or the clawed thumbs at the top of each wing. These awkward landings often cause fights among flying foxes, especially upon their return to camp at dawn. A single bad landing can cause an entire bat-laden tree to become highly agitated, full of fighting and screaming residents.People have eaten flying foxes for ages. Samoans, who call the flying fox manu lagi, animal of the heavens, use branches bound to the end of long poles to swat the winged delicacy from the sky. Aborigines in Australia build fires beneath flying fox camps--the smoke stupefies the prey--and use boomerangs to knock the creatures to the ground. UNIX and its attendant programs can be unruly beasts. Nutshell Handbooks(R) help you tame them....Edie Freedman designed this cover and the entire UNIX bestiary that appears on other Nutshell Handbooks. The beasts themselves are adapted from 19th-century engravings from the Dover Pictorial Archive. The cover layout was produced with QuarkXPress 3.1 using the ITC Garamond font.The inside layout was designed by Edie Freedman and implemented by Lenny Muellner in sqtroff using ITC Garamond Light and ITC Garamond Book fonts. The figures were created in Aldus Freehand 3.1 by Chris Reilley. The colophon was written by Michael Kalantarian.